This invention relates to a database wherein each record is made up of a record part of a relational database and a record part of a nonrelational database, and to a computer-readable recording medium recorded with a program for managing this database structure.
Conventionally, relational database systems and nonrelational database systems have been constructed as separate systems. Here, a relational database is a database made up only of data satisfying a normal form, and a nonrelational database is a database which is not limited to a normal form and is made up of either parent record parts only or parent record parts having one or more child record parts linked thereto. In systems having both a relational database system and a nonrelational database system of the configurations described above, data is converted in both directions between the relational database and the nonrelational database when data of the two systems is exchanged.
For example systems of financial institutions such as banks, life insurers, insurers and stockbrokerage companies have an off-line system using a relational database system and an on-line system using a nonrelational database system. In the on-line system, for example payment and receipt transactions inputted from terminals at branches are transmitted to a central facility and on the basis of these transactions data manipulation such as reference to and updating of the nonrelational database is carried out. The off-line system is operated for example from when the on-line business finishes, and on-line data is converted into off-line data to incorporate log information accumulated in the on-line system into the off-line relational database. Then, by performing relational operation and data manipulation processing on the off-line relational database, for example daily and monthly various statistical tables and documents are outputted and distributed to branches and return of information is thereby carried out. Also, by connecting this off-line relational database to a network, highly flexible non-fixed-form querying from branches and head office departments is made possible.
In a conventional normalized relational database, records are made up of relational lines only. That is, actual relational database systems have been developed with only the concept of `relational line`=`record`. Therefore, with respect to data for which this relational database structure is not ideal, for example in terms of processing efficiency or in terms of business processing, in practice inevitably a separate database system like the on-line system of a financial institution described above has had to be built and operated.
However, with the conventional configuration wherein a relational database and a nonrelational database are constructed as separate systems, because the database is made up of two systems there has been the problem that the work of development, operation and maintenance and the like is complex. Also, because costs of development, operation and maintenance and so on are duplicated, there has been the problem that the system is expensive.
In the financial institution system described above, great expenditure is required for the development of the on-line system and for the development of the off-line system. Also, the operating hours of the on-line system and the off-line system are different and there is the problem that because the off-line business is started after the on-line business ends the overall operating time of the financial institution system is long.
Also, sometimes, when data manipulation such as updating and deleting is to be carried out on a predetermined data set of a nonrelational database constructed as a separate system, a relational operation is carried out on the relational database system to extract a predetermined record set from the relational database and then a data set is extracted from the nonrelational database on the basis of for example matching of keys with the extracted relational database records and the data manipulation of updating and deleting or the like is then carried out on the data set thus extracted from the nonrelational database. In this case, both the relational database and the nonrelational database must be read. Because the relational database and the nonrelational database constructed as separate systems are held in physically or logically separate drives, in a database system using a virtual space system, when both databases are read, paging occurs. Consequently, when both databases are read, paging occurs frequently and the throughput of the system falls.
From the point of view of the reliability of the database system also, non-matching of data between the databases readily occurs, and because there is generally a time lag between the two systems such non-matching of data is liable to go unnoticed, and this causes serious problems in business execution.
A data system disclosed in Unexamined Published Japanese Application No. S.62-209615 uses a non-normal form relational system including repeat items, but this system still presupposes a relational database and does not have the object of integrating a relational database and a nonrelational database.